I have seen servos that are upwards of 170 grams and produce 40kg of torque.

I am betting these would make awesome pull pull rudder servos for something like a 50cc Yak.

Question is would they also work for aileron and elevator servos as well?

I could be wrong but at 50cc size I would not think the difference of a 150 grams total spread over a few servos would make too big a fuss. (I mean you could strap a couple of GoPros to one and be fine, and they weigh more than that.)

I would however be nervous about the sizing. (Apart from the rudder one. That one is a gimmie. Plenty of room and solid wood)

fhhuber

01-30-2014 08:18 PM

Depends on the 50cc size plane, which control surface and how you plan to fly it.

You could fly a 50cc Extreme Flight Yak with as low power as 110/130 in-oz rated HS-5625 ALL AROUND for very mild laps around the field... but you need 180+ in-oz on elevators, 200+ on ailerons and 250+ on rudder for aggressive 3D... 333 in-oz HS-7954 all around would be a good choice for ensuring you have the power for everything the plane can do...

Cool. The regular servos are like 300oz in. (25kg) but this one big one was 40kg... For 1/5th scale dune buggies :D

I will pop it on the rudder and never worry.

You gave me a lot of confidence just now... Thanks!

kyleservicetech

01-31-2014 01:40 AM

Quote:

Originally Posted by GunnyJeeves
(Post 938506)

I have seen servos that are upwards of 170 grams and produce 40kg of torque.

I am betting these would make awesome pull pull rudder servos for something like a 50cc Yak.

Question is would they also work for aileron and elevator servos as well?

I could be wrong but at 50cc size I would not think the difference of a 150 grams total spread over a few servos would make too big a fuss. (I mean you could strap a couple of GoPros to one and be fine, and they weigh more than that.)

I would however be nervous about the sizing. (Apart from the rudder one. That one is a gimmie. Plenty of room and solid wood)

I've got two giant scale models, both running Hacker A60 motors. One at 3000 watts, the other at about 2200 watts.

All servos in both models are the Hitec 645MG units. They seem to have plenty of power for the type of models I'm flying. Of course they don't do 3D.

Hitec 645 may be OK in some models at 20cc size (2000 watts) but they are just wrong for a 50cc model.

kyleservicetech

01-31-2014 04:35 AM

Quote:

Originally Posted by fhhuber
(Post 938571)

Hitec 645 may be OK in some models at 20cc size (2000 watts) but they are just wrong for a 50cc model.

Yeah

When you get into 50 cc and larger gassers, servos are a whole different ball game. Not only do they have to provide sufficient force to move and hold the surface they are connected to, they also have to handle the tremendous vibration from that gasoline engine up front.

If anyone has watched one of those giant scale models with a 50 cc engine running, you can see the elevator/rudder/ailerons all hammering the servos. Just sitting on the ground with the engine idling.

One of my club members has a big twin cylinder engine up front, with four high powered $$$$ servos on the rudder alone. Those giant scale models get expensive, real quick.

fhhuber

01-31-2014 04:54 AM

Idle of a single cyl gasser is a very high load for the servos... very true. It can impose loads as high as aggressive 3D in some cases. Multicylinder smooths it out considerably.

Just going appx 10% above idle can drastically reduce load on the servos.

Again... e-power doesn't deal with this issue. I have 3 e-power motors in the 20cc to 50cc power range. MUCH smoother at low throttle. But essentially no difference in servo loads in flight. (according to Eagletree loggers and Spektrum telemetry, judging by voltage drop at the RX)

kyleservicetech

01-31-2014 07:13 AM

Quote:

Originally Posted by fhhuber
(Post 938579)

Idle of a single cyl gasser is a very high load for the servos... very true. It can impose loads as high as aggressive 3D in some cases. Multicylinder smooths it out considerably.

Just going appx 10% above idle can drastically reduce load on the servos.

Again... e-power doesn't deal with this issue. I have 3 e-power motors in the 20cc to 50cc power range. MUCH smoother at low throttle. But essentially no difference in servo loads in flight. (according to Eagletree loggers and Spektrum telemetry, judging by voltage drop at the RX)

Back about two years ago I put together a "G" meter that was capable of measuring G forces, by measuring it twenty thousand times a second. That thing was used to measure vibration levels at the aileron servo location of a club members giant scale model. The model used a twin cylinder engine up front. Vibration levels measured directly on the servo case over-ranged my G meter at over 25 G's.